TECHNICAL FIELD

The disclosure relates to a method for manufacturing a brass component for a sanitary fitting, a component for a sanitary fitting manufactured according to the method and a sanitary fitting with a component manufactured according to the method.

BACKGROUND ART

Brass components are generally known, such as brass housings for sanitary fittings. These are usually produced by a casting process. In particular, there is a high demand for resistance to dezincification for sanitary fittings that are to be integrated into a wall, so-called "concealed fittings". Today, resistance to dezincification of cast brass fittings is usually achieved by arsenic doping of predominantly alpha brass crystallized components.

SUMMARY OF INVENTION

The disadvantage of the known cast fittings, however, is that they are generally limited in terms of their design possibilities. Furthermore, they usually require a comparatively large installation space or may be equipped with only comparatively few functions per installation volume.

Furthermore, additive manufactured components for sanitary fittings are known. Until now, ad ditive manufacturing has been used mainly for plastic components. However, the first additive manufacturing methods for metallic components, especially for brass components, have already been proposed. The well-known additive manufacturing methods for brass components use powders consisting of alloys containing zinc and copper in essentially equal parts. Such alloys crystallize to a large extent to beta solid solution, so that this alloy usually does not have sufficient dezincification resistance. Therefore, the known additive manufacturing processes cannot usually be used for the manufacturing of concealed valves.

Based on this, it is an object of the disclosure to solve, at least partially, the problems described in connection with the prior art. In particular, a method for manufacturing a brass component for a sanitary fitting should be specified by means of which the component may be designed in as many different ways as possible and/or manufactured as compactly as possible. In addition, the component manufactured with this method should be as resistant to dezincification as possible, so that it may be used for a concealed fitting in particular.

These tasks are solved by the features of the independent claims. Further advantageous configurations of the solution proposed here are indicated in the dependent claims. It should be noted that the features individually listed in the dependent claims may be combined in any technologically meaningful way and define further embodiments of the disclosure. In addition, the features indicated in the claims are specified and explained in more detail in the description, with further preferred embodiments of the disclosure being presented.

A method for manufacturing of a brass component for a sanitary fitting contributes to this, comprising at least the following steps: a. providing a material containing at least zinc and copper in powder form, wherein a mass ratio of zinc to copper is in the range of 0,4 to 0,85, b. layer-by-layer construction of the component by partial melting of the material with a laser.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 illustrates a flowchart of the method for the additive manufacture; and Fig. 2 illustrates a method described here for manufacturing a brass component for a sani tary fitting.

DESCRIPTION OF EMBODIMENTS

The sequence of steps a. and b. (Fig. 1) is exemplary and may be run through at least once in a regular operating procedure, for example. In particular, steps a. and b. may be carried out at least partially in parallel or even simultaneously. The method may be used, for example, for the additive manufacturing of a brass component of a sanitary fitting. In connection with the layer- by-layer production of brass components, the method indicates in particular a particularly ad vantageous possibility of providing a brass component that is advantageously resistant to dezin- cification. In particular, the method allows for the first time advantageously dezincification-re- sistant brass components to be produced using additive manufacturing or 3D printing.

The component is built up layer by layer by partial melting of the metallic material with a laser. The use of the laser or at least one laser beam allows in an advantageous way that the melting may take place as quickly as possible and/or the material may be heated to a comparatively high temperature for melting. This contributes in a particularly advantageous way to the fact that zinc and copper may be melted as safely as possible in the described ratio and the desired properties (especially the advantageous dezincification resistance) may be produced. In particu lar, the laser may be used to advantageously produce alloys that are not stable in casting or other melting processes.

Layer-by-layer construction may also be described as forming several layers one after the other, one on top of the other or layer-wise. A layer essentially describes a horizontal cross-section through the component. In partial melting, a powder located within a layer may be heated lo cally, at predetermined points where material solidification is to occur, for so long and/or so intensively that the metal powder grains there (briefly) liquefy and thus permanently (or until re- heated) bond together. Partial melting may be carried out advantageously in the form of 3D printing (in a powder bed) or in the form of a three-dimensional, additive manufacturing method (in a powder bed and/or with laser melting).

Laser sintering and/or laser melting may be performed in step b(Fig. 1). In step b. a so-called se lective laser sintering (short: SLS) is particularly preferred. Selective laser sintering (SLS) is an additive manufacturing method for producing spatial structures by sintering with a laser from a powdered starting material. Alternatively or cumulatively, a so-called selective laser melting (short: SLM) may be performed in step b.

The laser power(s) and/or the melting temperature(s) and/or the exposure time(s) of the laser may be selected and/or controlled in such a way that on the one hand there is enough time for a molten mixing of the different metals and on the other hand the time is short enough to avoid segregation as far as possible. The (maximum) cooling rate may be less than 10 ⁶ K/s [Kelvin per second]. The cooling rate may be in the range of 20 K/s to 2.000 K/s. With regard to the melting temperatures, the following ranges are preferred depending on the metal to be processed: for Cu greater than 1.100 °C, for Zn greater than 450 °C, for stainless steel greater than 1.500 °C, for CuZn greater than 900 °C. Particularly through a short melting time, materials with very different melting points may be advantageously alloyed together.

According to an advantageous configuration, it is suggested that a powder bed is formed in step a. (see Fig. 1). This allows a particularly simple and controlled provision of the material in an advantageous way. In this context, bimetallic laser sintering in a metal printer with powder bed may be carried out in particular.

According to a further advantageous configuration, it is proposed that in step a. an alloy containing at least zinc and copper is provided in powder form. In other words, this may be de scribed in particular as providing a powder whose powder particles are (already) formed with or from an alloy containing at least zinc and copper (brass alloy). The alloy may also contain ar senic and/or lead. In particular, a CuZnAs- or a CuZnAsPb alloy in powder form may be used.

According to a further advantageous configuration, it is proposed that in step b. an alloy containing at least zinc and copper is produced by alloying in the laser beam. In other words, this may be described in particular in such a way that the alloying (only) takes place during the layer-by-layer construction or during selective melting with the laser. Only those parts of the powder may be selectively alloyed which contribute to the construction of the component or which are to remain in the component.

In this context, (separate) zinc powder and copper powder (in the ratio described) may be used in particular to form the powder bed. These may be mixed or blended together (physically and/or uniformly) to provide the material or to form the powder bed. Furthermore, the zinc powder and the copper powder may be mixed with an arsenic powder and/or a lead powder to provide the material or to form the powder bed. Zinc powder and/or copper powder may (alternatively) be used, which are already at least partially (pre-)alloyed or chemically bonded with arsenic and/or lead.

According to a further advantageous configuration, it is proposed that the material after melt ing crystallizes at least predominantly to alpha brass. At least 80% of the material may crystal lize to alpha brass. The alpha brass usually has an advantageous dezincification resistance.

According to a further advantageous configuration, it is proposed that the mass ratio of zinc to copper is 0,52 or more. According to a further advantageous configuration, it is proposed that the mass ratio of zinc to copper is 0,55 or more. According to a further advantageous configuration, it is proposed that the mass ratio of zinc to copper is 0,75 or less. According to a further advantageous configuration, it is proposed that the mass ratio of zinc to copper is 0,7 or less. In this range a favourable dezincification resistance may be achieved. Furthermore, the mass ratio of zinc to copper may be about 0,62. According to a further advantageous configuration, it is proposed that the mass ratio of zinc to copper is 0,6 or less. According to a further advantageous configuration, it is proposed that the mass ratio of zinc to copper is 0,68 or more. Accord ing to a further advantageous configuration, it is proposed that the mass ratio of zinc to copper is 0,76 or more. In this way a particularly advantageous dezincification resistance may be achieved, especially without the addition of arsenic and/or lead.

According to a further advantageous configuration, it is proposed that the material further con tains arsenic (As). By adding (doped) arsenic, the alpha brass may be stabilized. The addition of (doped) arsenic may (further) increase corrosion resistance and/or dezincification resistance. It was determined that adding arsenic to alpha brass results in an improved stability, in particular with regard to (intercrystalline) corrosion, compared to adding As to beta brass. Arsenic may be responsible for binding copper electrons in the alpha brass and therefore to influence the elec trochemical potential of grain boundaries. This may lead to the improved corrosion resistance of the material, in particular concerning corrosion when being exposed to soft water (e.g.

~ 50 °C; approx. 5 °dH-8 °dH, approx. 20 mg/I chlorides) over a long period of time.

During dezincification, the zinc-rich, electrochemically somewhat less noble beta phase of the structure is selectively dissolved, which corresponds to the type of selective corrosion. The re leased copper ions are very often found here cemented back metallically in the structure as copper-colored precipitates. The reason for this lies in the electrochemically very noble mate rial character of copper; the redox potential of the precipitation reaction (copper ions to metal lic copper) is higher than the redox potential of the surrounding material, which is then corre spondingly oxidized, i.e. corroded, during this reaction. As already stated above, arsenic may in fluence this electrochemical potential and therefore lead to an improved dezincification resis- tance. For example, arsenic may be added to copper and/or zinc during powder production. Arsenic is preferably added to copper. The mass fraction of arsenic, for example, may be in the range of 0,01 to 0,25%. Preferably the mass fraction of arsenic may be 0,1 or more. Preferably the mass fraction of arsenic may be 0,09 or more. Preferably the mass fraction of arsenic may be 0,19 or less. Preferably the mass fraction of arsenic may be 0,18% or less. Preferably the mass fraction of arsenic may be 0,17%.

According to a further advantageous configuration, it is proposed that the material further con tains lead. If lead is present, this may be provided, for example, with a mass fraction of 0,01 to 1,5%, preferably 0,1 to 0,3% and in particular about 0,15%. However, it may (alternatively) be provided that the material does not contain lead. In this context, the material may consist of zinc and copper (in the ratio described) or of zinc, copper, and arsenic.

According to another aspect, a component for a sanitary fitting is proposed, wherein the component is manufactured by a method described here. The component may be a housing or a housing part of a sanitary fitting, for example.

According to another aspect, a sanitary fitting is also proposed, comprising a component manu factured by a method described here. In this context, the sanitary fitting may also have a component described here. The sanitary fitting may be, for example, a washbasin fitting, bathtub fitting, concealed fitting or the like.

The details, features and advantageous designs discussed in connection with the method may also occur in the component and/or sanitary fitting presented here and vice versa. In this re spect, full reference is made to the explanations there for a more detailed characterization of the features. The solution presented here as well as its technical environment will be explained in more de tail in the following using the figures. It should be noted that the disclosure is not to be restricted by the shown embodiments. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in or in connection with the figures and combine them with other components and/or findings from other figures and/or the present description. It shows exemplary and schematic:

Fig. 2 shows an exemplary and schematic illustration of a method described here for the manu facturing of a brass component 1 for a sanitary fitting 2. In the method, a material 3 containing at least zinc and copper is provided in powder form. The mass ratio of zinc to copper is in the range of 0,4 to 0,85. A layer by layer construction or additive manufacturing of the component 1 is carried out by partial melting of the material 3 with a laser 4.

A powder bed 5 may be formed to provide the material. Furthermore, an alloy containing at least zinc and copper may be provided in powder form to provide the material.

An alloy containing at least zinc and copper may be produced (as an alternative to the provision as an alloy) during the layered construction by alloying in the laser beam. After melting, the ma terial may at least predominantly crystallize to alpha brass.

The mass ratio of zinc to copper, for example, may be in the range of 0,55 to 0,7. In a particu larly advantageous configuration, the mass ratio of zinc to copper is circa 0,62.

Material 3 may optionally further contain arsenic. The mass fraction of arsenic, for example, may be in the range of 0,01 to 0,25%, especially about 0,17%. Material 3 may optionally further contain lead. Material 3 may optionally further contain tin. Thus, a method for manufacturing a brass component for a sanitary fitting, a component manu factured by the method and a sanitary fitting with a component manufactured by the method are specified, which at least partially solve the problems described in connection with the state of the art. Due to the additive manufacturing method, the component may be designed in as many different ways as possible, especially with very thin wall thicknesses, and/or manufac tured as compactly as possible. In addition, the component manufactured by this method may be as resistant to dezincification as possible due to the material composition described, so that it may also be used for a concealed fitting in particular.